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Abstract:

A medical device with an expandable element and expandable tubular sleeve
surrounding at least a portion of the expandable element which influences
the rate, shape and/or force required to expand the expandable element
and methods for use in a body lumen are provided.

Claims:

1. A medical device comprising: (a) an elongated tubular body with a
proximal and distal end; (b) at least one expandable element at the
distal end of the elongated tubular body; and (c) an expandable tubular
sleeve surrounding at least a portion of the expandable element, said
expandable tubular sleeve comprising at least two portions with differing
compression ratios.

2. The medical device of claim 1, wherein the expandable element is a
balloon.

3. The medical device of claim 1, wherein the expandable element is
self-expanding.

5. The medical device of claim 1, wherein the expandable element has a
uniform thickness.

6. The medical device of claim 1, wherein the expandable tubular sleeve
has a uniform wall thickness after expansion.

7. The medical device of claim 1, wherein the expandable tubular sleeve
has a uniform wall thickness prior to expansion.

8. The medical device of claim 1, wherein the expandable tubular sleeve
is affixed to the expandable element.

9. The medical device of claim 1, wherein the expandable tubular sleeve
comprises one or more materials having a porous microstructure.

10. The medical device of claim 9, wherein the material is expanded
polytetrafluoroethylene.

11. The medical device of claim 9, wherein the material is ultra high
molecular weight polyethylene.

12. The medical device of claim 9, wherein the material is fibrillated.

13. The medical device of claim 1, wherein differing compression ratios
of the at least two portions of the expandable tubular sleeve influence
rate of expansion of the expandable element.

14. The medical device of claim 1, wherein differing compression ratios
of the at least two portions of the expandable tubular sleeve influence
shape of the expandable element upon expansion.

15. The medical device of claim 1, wherein differing compression ratios
of the at least two portions of the expandable tubular sleeve influence
amount of force required to expand the expandable element.

16. The medical device of claim 1, wherein the expandable tubular sleeve
is a single continuous material.

17. The medical device of claim 1, wherein the expandable tubular sleeve
comprises a distal end portion, a proximal end portion and a central or
middle portion.

18. The medical device of claim 17, wherein the distal end portion and
the proximal end portion exhibit with increased compressive ratio as
compared to the central or middle portion.

19. A method of treating a site in a body lumen, said method comprising
the steps of: positioning within a body lumen the medical device of claim
1 so that the expandable element in folded form is adjacent to a
treatment site; and expanding the expandable element at a pressure or
force sufficient to expand the expandable element at a first portion of
the expandable tubular sleeve.

20. The method of claim 19, further comprising expanding the expandable
element at an increased rate or pressure to expand the expandable element
at a second portion of the expandable tubular sleeve with greater
compressive ratio than the first portion.

22. The method of claim 21, wherein said interventional device is a
stent.

23. The method of claim 21, wherein said interventional device is a heart
valve.

24. The method of claim 19, wherein said treatment site is a coronary
artery.

25. The method of claim 19, wherein the expandable element is a balloon.

26. The method of claim 19, wherein said expandable tubular sleeves
comprises at least one polymer.

27. The method of claim 26, wherein said polymer is expanded
polytetrafluoroethylene.

Description:

BACKGROUND OF THE INVENTION

[0001] Vascular dilatation balloons on medical devices generally fall into
two classes. The first class of vascular dilatation balloons comprises a
noncompliant balloon formed from a relatively nondistensible material
such as polyethylene terephthalate (PET). Noncompliant balloons exhibit a
substantially uniform exterior inflated profile which remains
substantially unchanged upon increasing inflation pressures. Noncompliant
balloons have been suggested to be advantageous because they allow the
introduction of increased inflation pressure to break calcified lesions
while retaining a predictable inflation profile thus minimizing damage to
the surrounding lumen. Non-limiting examples of noncompliant balloons are
disclosed in U.S. Pat. No. 6,200,290 to Burgmeier and Published
Application U.S. 2010/0022949 to Eidenschink. Additional examples are
commonly known in the art.

[0002] The second class of vascular dilatation balloons comprises
compliant balloons. Compliant balloons expand in diameter upon increased
inflation pressure. A problem with compliant balloons has been that upon
inflation within a lesion, the balloon inflates unevenly around the
plaque to form an hour glass type shape. The uneven inflation of the
compliant balloon can result in damage to the lumen as well as failure to
alleviate the stenosis. Non-limiting examples of compliant balloons are
disclosed in U.S. Pat. No. 6,120,477 to Campbell et al. and U.S. Pat. No.
6,890,395 to Simhambhatla, each of which is incorporated by reference
herein in its entirety. Additional examples are commonly known in the
art.

[0003] It is not uncommon with either types of balloons to have some
difficulty in properly positioning the balloon, which are usually located
on the distal ends of catheters, within the region of the lesion of a
patient's artery or other body lumen or, if properly positioned within
the lesion, to have difficulty in maintaining the position of the
inflatable member or balloon within the lesion during balloon inflation.

[0004] What is needed is a balloon which can be preferentially inflated in
different sections to better control the position of the balloon and to
provide a more uniform pressure against the lesion during the dilatation.
In addition, there is a need for a balloon that can be preferentially
inflated in different sections to more precisely expand an interventional
device at the site of a lesion. Although U.S. Pat. No. 5,470,313 and U.S.
Pat. No. 5,843,116 disclose focalized intraluminal balloons with variable
inflation zones or regions, the present invention allows any type of
balloon to be preferentially inflated at different sections without
modifying the balloon or delivery catheter.

SUMMARY OF THE INVENTION

[0005] An aspect of the present invention relates to a medical device
comprising an elongated tubular body with a proximal and distal end, at
least one expandable element at the distal end of the elongated tubular
body, and an expandable tubular sleeve surrounding at least a portion of
the expandable element. The expandable tubular sleeve comprises at least
two portions with differing radial strengths thereby influencing the
shape of the expandable element and surrounding tubular sleeve and/or the
amount of force required to expand the expanding element and/or
surrounding tubular sleeve.

[0006] Another aspect of the present invention relates to a method of
treating a site in a body lumen. The method comprises providing a medical
device comprising an elongated tubular body with a proximal and distal
end, at least one expandable element at the distal end of the elongated
tubular body, and an expandable tubular sleeve surrounding at least a
portion of the expandable element. The expandable tubular sleeve
comprises at least two portions with differing radial strengths which
influence the shape and/or force required to inflate the expandable
element and/or surrounding expandable tubular sleeve. The medical device
is positioned within a body lumen so that the expandable element in
folded form is adjacent to a treatment site. The expandable element is
then inflated at a pressure or force sufficient to inflate the expandable
element at a first portion of the expandable tubular sleeve. If needed,
the expandable element can be inflated at an increased pressure to
inflate the expandable element at a second portion of the expandable
tubular sleeve with greater radial strength than the first portion.

[0007] The operation of the present invention should become apparent from
the following description when considered in conjunction with the
accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

[0008]FIG. 1 is a schematic illustration of an expandable element in
expanded form of a medical device of the present invention.

[0009]FIG. 2 is a schematic illustration of an expanded element in folded
form of a medical device of the present invention.

[0010]FIG. 3 is a schematic illustration of a medical device of the
present invention with an expandable sleeve with regions of varying
radial strengths covering the folded expandable element.

[0011]FIG. 4 is schematic illustration of a medical device of the present
invention expanded at a first portion.

[0012]FIG. 5 is a schematic illustration of medical device of the present
invention expanded in full at first and second portions.

[0013]FIG. 6 is a side view of an expanded balloon showing typical
dimensions.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention relates to medical devices with an expandable
portion for insertion into the body lumen. More particularly, the present
invention relates to balloon dilatation catheters for insertion in the
vascular system. In one embodiment, the balloon dilatation catheter is a
focal balloon dilatation catheter, meaning that expansive energy of the
balloon is focused at one or more predetermined regions along the surface
of the balloon.

[0015] Medical devices of the present invention comprise an elongated
tubular body with a proximal and distal end, at least one expandable
element at the distal end of the elongated tubular body, and an
expandable tubular sleeve surrounding at least a portion of the
expandable element.

[0016] One embodiment of the invention comprises a medical device
comprising: an elongated tubular body with a proximal and distal end; (b)
at least one expandable element at the distal end of the elongated
tubular body; and (c) an expandable tubular sleeve surrounding at least a
portion of the expandable element, said expandable tubular sleeve
comprising at least two portions with differing compression ratios. In
another embodiment, the expandable element is a balloon. In another
embodiment, expandable element is self-expanding. In another embodiment,
the expandable element is mechanically expanded. In another embodiment,
the expandable element has a uniform thickness. In another embodiment,
the expandable tubular sleeve has a uniform wall thickness after
expansion. In another embodiment, the expandable tubular sleeve has a
uniform wall thickness prior to expansion.

[0017] Elements of the medical device of the present invention are
depicted in FIGS. 1 through 5.

[0018] Specifically, FIGS. 1 and 2 are illustrative of a general balloon
catheter 100 having an elongated tubular body 102 with an expandable
element 104.

[0019] The elongated tubular body 102 has a proximal control end 106 and a
distal functional end 108. The balloon catheter also has a proximal
guidewire lumen 110 that extends through the length of the elongated
tubular body 102 and exits the distal end at a guide wire port 112. The
balloon catheter shown is an "Over The Wire" configuration, as commonly
known in the art. As an alternate, the catheter could have a
mid-guidewire port and therefore have a "Rapid Exchange" configuration,
as commonly known in the art. The balloon catheter 100 also incorporates
a proximal inflation port 114 that allows fluid communication between the
inflation port 114 and the inflatable element 104. The length and inner
and outer diameter of the tubular body are selected based upon the
desired application of the medical device. For example, in one
nonlimiting embodiment, wherein the medical device is used in
percutaneous transluminal coronary angioplasty, the length of the tubular
body typically ranges from about 120 cm to about 140 cm. In this
embodiment, the outer diameter of the tubular body ranges from about
0.026 inches to about 0.45 inches. As will be understood by the skilled
artisan upon reading this disclosure, the length and/or diameter of the
tubular body are in no way limiting and may be routinely modified for
various applications of the medical devices of the present invention. The
tubular body generally has a circular cross-sectional configuration.
However, triangular and oval cross-sectional configurations can also be
used.

[0020] The tubular body must have sufficient structural integrity to
permit the medical device to be advanced to distal vascular locations
without bending or buckling upon insertion. Various techniques are known
for manufacturing the tubular bodies. In one embodiment, the tubular body
is manufactured by extrusion of a biocompatible polymer.

[0021] In another embodiment, the present invention comprises a catheter,
an expandable tubular sleeve, and an expandable member for expanding an
interventional device, said expandable member preferentially inflated at
different sections to better control the expansion of said implantable
medical device. Non-limiting examples of said interventional devices are
stents (which include stent-grafts), and heart valves.

As shown in FIGS. 3 through 5, the medical device of the present
invention comprises an expandable tubular sleeve 300 surrounding at least
a portion of the expandable element 104. The expandable tubular sleeve
comprises one or more materials having a porous microstructure. Examples
of suitable materials include, but are not limited to expanded
polytetrafluoroethylene (ePTFE) and ultra high molecular weight
polyethylene (UHMW PE). Thus, in one embodiment, the expandable tubular
sleeve comprises one or more materials having a porous microstructure. In
another embodiment, the material is fibrillated. In another embodiment,
the material comprises ePTFE. In another embodiment, the material is UHMW
PE. In another embodiment, the expandable tubular sleeve is affixed to
the expandable element.

[0023] The expandable tubular sleeve comprises at least two portions with
differing radial strengths. In one embodiment, as depicted in FIGS. 3
through 5, the expandable tubular sleeve 300 comprises a distal end
portion 302 and a proximal end portion 304 with increased radial strength
as compared to a central or middle portion 306. In this embodiment, as
depicted in FIG. 4, the central portion 306 inflates first under less
expansion pressure while the distal end portion 302 and proximal end
portion 304 expand second only under additional expansion pressure. In
another embodiment, the differing radial strengths of the portions of the
expandable sleeve influence the shape of the expandable element and
surrounding tubular sleeve. In another embodiment, the differing radial
strengths of the portions of the expandable sleeve influence the amount
of force required to expand the sleeve.

[0024] The tubular expandable sleeve may comprise a single continuous
material. In one embodiment, the single continuous material expandable
sleeve is comprised of a polymer having a node and fibril
micro-structure. Refer to U.S. Pat. No. 3,962,153, which is incorporated
by reference herein in its entirety. A tube of such material can be
placed onto a mandrel, longitudinally compressed and heat treated to
preserve the compressed state. Refer to U.S. Pat. No. 5,308,664, which is
incorporated by reference herein in its entirety. The amount of
longitudinal compression dictates the amount of radial strength. More
longitudinal compression results in a higher degree of radial strength
(i.e. the higher compression ratio). A continuous tube can therefore have
discrete zones with varying amounts of longitudinal compression
(compression ratio) resulting in discrete zones of radial strength. The
varied radial strengths will then dictate the inflation profiles (or
sequence) of an expandable element.

[0025] A continuous tube having discrete zones of radial strength
according to the present invention can incorporate varying wall
thicknesses and cross-sectional profiles. For example a continuous tube
can have a circular, oval, triangular, square, rectangular or polygon
cross-sectional shape. The tube can also incorporate wall sections of
varying thickness. Various cross-sectional profiles and various wall
thicknesses can be combined along a single tube.

[0026] Continuous tubes having discrete zones of radial strength according
to the present invention can also incorporate lubricious coatings, drug
eluting coatings, anti-microbial coatings, visualization aids or other
additions that enhance the device function.

[0027] Various "staged inflation" balloon profiles can be derived by the
use of an expandable sleeve that has discrete zones of varying radial
strength. For example, a sleeve may be configured to have a weak (or easy
to expand) zone on one end of a balloon, combined with other zones of
stronger radial strength. Such a balloon would initially inflate on the
one end (at a first pressure) and then progressively inflate along the
balloon length at higher pressures. A balloon can have 2, 3, 4, 5, 6, 7,
8, 9, 10 or more discrete zones of varying radial strength. The various
discrete zones of radial strength can be arranged along the balloon in
any desired order. The radial strength of the discrete zones may also be
individually tailored to expand with any desired pressure. The discrete
zones of radial strength can be combined with non-expandable zones or
with zones of very low radial strength. Multiple sleeves having discrete
zones of radial strength can be combined in a longitudinal or co-axial
configuration. An expandable sleeve having discrete zones of varying
radial strength can be positioned externally or internally to the
expandable element.

[0028] In one embodiment, the tubular expandable sleeve comprises ePTFE.
It may be desirable to modify the ePTFE used for the present invention by
incorporating various additives with said ePTFE. Fillers can be
incorporated in ePTFE by known methods, such as the methods taught by
U.S. Pat. No. 5,879,794, to Korleski. Additives can also be imbibed into
the ePTFE by known methods. Additives can also be coated on the ePTFE by
known methods. Suitable additives include, for example, materials in
particulate and/or fiber form and can be polymers, adhesives, elastomers,
ceramics, metals, metalloids, carbon, and combinations thereof.
Particularly useful additives include, for example, radiopaque materials,
such as certain metals (e.g. barium alloys) and carbon. The additives can
be used in combination with desired adhesive materials when incorporated
with the polymer. It may also be desirable to metalize the ePTFE or at
least a portion thereof. An additive may be included in the matrix of the
polymer itself, or contained within the voids defined by the polymeric
structure, or both. Desirable fillers may also include colorants,
medicaments, anti-microbials, antivirals, antibiotics, antibacterial
agents, anti-inflammatory agents, anti-proliferative agents,
anti-coagulating agents, hemostatic agents, analgesics, elastomers and
mixtures thereof. Compounds which lubricate an ePTFE cover, thus allowing
the material to slide smoothly across another material, can be used to
coat, fill, or imbibe the tubular cover. Solid lubricants (i.e. graphite,
waxes, silicone), fluid lubricants (i.e. hydrocarbon oils, silicone
oils), gels (i.e. hydrogel) or any other biocompatible material known in
the art may be used. In one embodiment, said expandable sleeve is coated,
filled or imbibed on only one side. In another embodiment, said
expandable sleeve is coated, filled or imbibed on both sides. In another
embodiment, said expandable sleeve is coated, filled or imbibed on only
one side and coated, filled or imbibed one the other side with a
different material.

[0029] An expandable sleeve having discrete zones of radial strength, can
dictate the expansion profile or sequence of an underlying (or overlying)
expandable element. The controlled expansion profile or expansion
sequence can be used to enable or improve various medical and industrial
applications. For example, stents that are easily longitudinally
compressed during expansion can be expanded by the balloon and cover of
the present invention. Said stent can be expanded from the center out,
thus maintaining the stent longitudinally tensioned as it is expanded. An
example of such a stent is described in U.S. Patent Application
Publication U.S. 2009/0182413, incorporated by reference herein for all
purposes. The longitudinal tension prevents the stent from being
longitudinally compressed. In an opposite configuration the balloon and
cover can expand from the ends in towards the center and thereby compress
the overlaying device. A heart valve stent may require a stent that is
expanded in a specific "hour-glass" shape, wherein the hour-glass shape
is developed in a specific sequence. In other applications the expansion
can begin at one end and progress to the opposing end of the expansible
element, thereby creating a "pushing" or peristaltic motion. In one
embodiment, said stents can comprise 316L stainless steel,
cobalt-chromium-nickel-molybdenum-iron alloy ("cobalt-chromium"), other
cobalt alloys such as L605, tantalum, Nitinol, or other bio-compatible
metals. In another embodiment, the stent can be a self expanding stent, a
balloon expandable stent or a combination thereof.

[0030] In one embodiment, the thickness of the sleeve wall is selected to
have a uniform wall thickness prior to expansion In another embodiment,
the thickness of the sleeve wall is selected to have a uniform wall
thickness after expansion In another embodiment, the thickness of the
sleeve wall is selected to have a uniform wall thickness prior to and
after expansion.

[0031] The expandable tubular sleeve may be affixed to the expandable
element or may be slidably positioned around the expandable element
without a separate affixation means.

[0032] As shown in FIGS. 1 and 2, at least one expandable element 104 is
provided at the distal end of the tubular body. An example of an
expandable element useful in the present invention is an inflation
balloon. Other forms of expandable elements include, but are not limited
to mechanical expanders such as "Chinese Lanterns", expandable bow-arms,
rotationally expandable/contractible coil springs, cam-type sliding
mechanisms, expandable linkages, expandable collets, polymeric or natural
materials that expand when activated and other configurations as commonly
known in the art. The expandable element used in the medical device of
the present invention may also be self-expanding (eliminated mechanically
expand). In one embodiment, the expandable element has an outer wall of
uniform thickness. The wall thickness can range from less than about 0.01
mm to about 5 mm. A typical 3 mm diameter thin walled noncompliant
balloon can have a wall thickness of about 0.02 mm.

[0033] The balloon members according to the present invention may be
formed from using any materials known to those of skill in the art.
Commonly employed materials include the thermoplastic elastomeric and
non-elastomeric polymers and the thermosets including the moisture
curable polymers.

[0034] Examples of suitable materials include but are not limited to,
polyolefins, polyesters, polyurethanes, polyamides, polyimides,
polycarbonates, polyphenylene sulfides, polyphenylene oxides, polyethers,
silicones, polycarbonates, styrenic polymers, copolymers thereof, and
mixtures thereof. Some of these classes are available both as thermosets
and as thermoplastic polymers. See U.S. Pat No. 5,500,181, for example.
As used herein, the term copolymer shall be used to refer to any
polymeric material formed from more than one monomer.

[0035] As used herein, the term "copolymer" shall be used to refer to any
polymer formed from two or more monomers, e.g. 2, 3, 4, 5 and so on and
so forth.

[0036] Useful polyamides include, but are not limited to, nylon 12, nylon
11, nylon 9, nylon 6/9 and nylon 6/6. The use of such materials is
described in U.S. Pat. No. 4,906,244, for example.

[0037] Examples of some copolymers of such materials include the
polyether-block-amides, available from Elf Atochem North America in
Philadelphia, Pa. under the tradename of PEBAX®. Another suitable
copolymer is a polyetheresteramide.

[0038] Suitable polyester copolymers, include, for example, polyethyelene
terephthalate and polybutylene terephthalate, polyester ethers and
polyester elastomer copolymers such as those available from DuPont in
Wilmington, Del. under the tradename of HYTREL®.

[0039] Block copolymer elastomers such as those copolymers having styrene
end blocks, and midblocks formed from butadiene, isoprene,
ethylene/butylene, ethylene/propene, and so forth may be employed herein.
Other styrenic block copolymers include acrylonitrile-styrene and
acrylonitrile-butadiene-styrene block copolymers. Also, block copolymers
wherein the particular block copolymer thermoplastic elastomers in which
the block copolymer is made up of hard segments of a polyester or
polyamide and soft segments of polyether.

[0041] Suitable materials which can be employed in balloon formation are
further described in, for example, U.S. Pat. No. 6,406,457; U.S. Pat. No.
6,284,333; U.S. Pat. No. 6,171,278; U.S. Pat. No. 6,146,356; U.S. Pat.
No. 5,951,941; U.S. Pat. No. 5,830,182; U.S. Pat. No. 5,556,383; U.S.
Pat. No. 5,447,497; U.S. Pat. No. 5,403,340; U.S. Pat. No. 5,348,538; and
U.S. Pat. No. 5,330,428.

[0042] The above materials are intended for illustrative purposes only,
and not as a limitation on the scope of the present invention. Suitable
polymeric materials available for use are vast and too numerous to be
listed herein and are known to those of ordinary skill in the art.

[0043] Balloon formation may be carried out in any conventional manner
using known extrusion, injection molding and other molding techniques.
Typically, there are three major steps in the process which include
extruding a tubular preform, molding the balloon and annealing the
balloon. Depending on the balloon material employed, the preform may be
axially stretched before it is blown. Techniques for balloon formation
are described in U.S. Pat. No. 4,490,421, RE32,983, RE33,561 and U.S.
Pat. No. 5,348,538.

[0044] The expandable element may be attached to the tubular body by
various bonding means known to the skilled artisan. Examples include, but
are not limited to, solvent bonding, thermal adhesive bonding and heat
shrinking or sealing. The selection of the bonding technique is dependent
upon the materials from which the expandable element and tubular body are
prepared. Refer to U.S. Pat. No. 7,048,713 to Wang, which is incorporated
by reference herein in its entirety, for general teachings relating to
the bonding of a balloon to a catheter.

[0045] Medical devices of the present invention are useful in treating
sites in a body lumen or delivering interventional devices as described
above. In one embodiment, the medical device of the present invention is
used in angioplasty procedure. In this method, the medical device of the
present invention is percutaneously advanced so that the expandable
element in folded form is adjacent to a vascular treatment site.
Generally the treatment site is a stenosis caused, for example, by plaque
or a thrombus. The expandable element of the medical device is then
inflated at a pressure or force sufficient to inflate the expandable
element. After the stenosis is compressed to or beyond the native
diameter of the lumen, the expandable element is evacuated and the
medical device is withdrawn from the body lumen. In another embodiment,
said medical devices of the present invention are useful for delivering
an interventional device to a treatment site.

[0046] One embodiment of the invention comprises a method of treating a
site in a body lumen, said method comprising the steps of positioning
within a body lumen the medical device of the invention so that the
expandable element in folded form is adjacent to a treatment site; and
inflating the expandable element at a pressure or force sufficient to
inflate the expandable element and to expand the expandable tubular
sleeve according to its varying radial strength, as described above. In
one embodiment, said expandable element expands an interventional device.
In another embodiment, said interventional device is a stent. In another
embodiment, said interventional device is a heart valve. In another
embodiment, said treatment site is a coronary artery.

[0047] The following nonlimiting examples are provided to further
illustrate the present invention.

EXAMPLE 1

[0048] A film tube was placed over a folded PET balloon. The film tube had
discrete zones having different amounts of radial strength, imparted by
varying amounts of longitudinal compression. The middle zone of the film
tube was longitudinally compressed 35%. The ends of the film tube were
longitudinally compressed 60%. The resulting balloon inflated first in
the middle zone when a first pressure was applied to the balloon. The
ends of the balloon inflated when a second, higher pressure was applied
to the balloon. The following example details a method of making a
particular "staged inflation" balloon.

[0049] An ePTFE film was helically wrapped around a mandrel having a
diameter of about 28.5 mm and a length of about 37 cm. The film width was
about 2.54 cm. Two passes of film were wrapped in opposing directions,
using a 2.794 mm pitch (measured from adjacent film edges) with a film
angle of about 78°. The wrapped length was about 30 cm.

[0050] The film wrapped mandrel was then placed into an air convection
oven heated to about 380° C. for about 28 minutes. This heat
exposure bonded the layers of ePTFE, forming a thin film tube.

[0051] The ePTFE film wrapped mandrel was removed from the oven, allowed
to cool, and the thin film tube was removed from the mandrel. The thin
film tube had a diameter of about 28.5 mm and a wall thickness of about
0.0254 mm.

[0052] The about 30 cm long thin film tube and was then tensioned by hand
and stretched longitudinally to about 400% of the original length, or to
about 120 cm. After stretching, the tube was placed onto a mandrel having
a diameter of about 4 mm and a length of about 130 cm. The stretched tube
was smoothed by hand onto the mandrel, forming a small diameter thin film
tube having a diameter of about 4 mm.

[0053] A temporary ePTFE film was then helically wrapped onto the about 4
mm diameter thin wall tube. The film thickness was about 0.00508 mm and
the film width was about 1.905 cm. One pass of film was wrapped, using a
2.6924 mm pitch (measured from adjacent film edges) with a film angle of
about 78°.

[0054] The thin film tube and temporary ePTFE film wrap was then
longitudinally compressed. The middle portion of the thin film tube had
an initial length of 33.75 mm and was compressed to a length of 25 mm.
The first end of the thin film tube had an initial length of 44 mm and
was compressed to a length of 27.5 mm. The second end of the thin film
tube was longitudinally compressed in a similar manner to the first end
of the thin film tube. The total length of the longitudinally compressed
thin film tube was about 80 mm.

[0055] The longitudinally compressed thin film tube and mandrel was then
placed into an air convection oven heated to about 380° C. for
about 1 minute.

[0056] The ePTFE film wrapped mandrel was then removed from the oven and
allowed to cool.

[0057] The temporary ePTFE film wrap was then removed from the thin film
tube. The resulting thin film tube had discrete zones of varying radial
strength.

[0058] The thin film tube was then placed over a catheter mounted,
compacted PET balloon. The balloon is shown in an expanded state in FIG.
6. The thin film tube having discrete zones of radial strength was
longitudinally centered onto the compacted balloon so that about 2 mm of
the balloon legs protruded from the thin film tube. The ends of the thin
film tube were secured to the balloon legs using 4981 Loctite
Cyanoacrylate adhesive and 0.635 cm wide ePTFE film wrapped around both
the thin film tube and the balloon leg.

[0059] The balloon was then pressurized to about 3 atm, inflating the
center section of the balloon as depicted in FIG. 4. When further
pressurized to about 12 atm, the proximal and distal ends of the balloon
inflated as shown in FIG. 5.

[0060] Numerous characteristics and advantages of the present invention
have been set forth in the preceding description, including preferred and
alternate embodiments together with details of the structure and function
of the invention. The disclosure is intended as illustrative only and as
such is not intended to be exhaustive. It will be evident to those
skilled in the art that various modifications may be made, especially in
matters of structure, materials, elements, components, shape, size and
arrangement of parts within the principals of the invention, to the full
extent indicated by the broad, general meaning of the terms in which the
appended claims are expressed. To the extent that these various
modifications do not depart from the spirit and scope of the appended
claims, they are intended to be encompassed therein. In addition to being
directed to the embodiments described above and claimed below, the
present invention is further directed to embodiments having different
combinations of the features described above and claimed below. As such,
the invention is also directed to other embodiments having any other
possible combination of the dependent features claimed below.